tailieunhanh - Ultra Wideband Part 3

Tham khảo tài liệu 'ultra wideband part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 54 Ultra Wideband Karlsson M. Hảkansson P. Gong S. 2008 A Frequency Triplexer for Ultra-Wideband Systems Utilizing Combined Broadside- and Edge-Coupled Filters IEEE Trans. on Advanced Packaging Vol. 31 No. 4 pp. 794-801 Nov. 2008 Pozar D. M. 2001 Microwave and RF Design of Wireless Systems John Wiley Sons Inc. ISbN 0-471-32282-2 USA 2001 Fusco V. F. 2005 Foundations of Antenna Theory and Techniques Pearson Education Limited Edinburgh Gate Harlow Essex England ISBN 0-130-26267-6 2005 4 Performance of a TH-PPM UWB system in different scenario environments Moez HIZEM and Ridha BOUALLEGUE Research Unit 6 Tel Sup Com Tunisia 1. Introduction Ultra Wideband UWB communication technology has attracted considerable attention by researchers in recent years because of its appealing features and its several applications it offers in many areas Win Scholtz 1998 Fontana 2007 Ghavami et al 2007 . An UWB system is characterised by very short-duration pulses usually on the order of a nanosecond with a low duty cycle. It offers low power transmission a fine path resolution and it easily supports multi-user communication Di Benedetto 2004 . These properties make UWB technology an attractive candidate for short-range high-speed wireless multiple access communication and ad hoc networking with simple baseband and the capability to overlay legacy wireless systems. All this gives us many features such as wireless radar communications networking imaging and positioning systems Yang Giannakis 2004 . Historically UWB systems are based on impulse radio IR concepts. In an IR UWB system a number of pulses are transmitted per information symbol and information is usually conveyed by the positions or the polarities of the pulses. In order that impulse radios operating in the highly frequency range below a few GHz do not interfere with narrowband radio systems operating in the same frequency band the use of spread-spectrum techniques is necessary. A simple mean to spread the spectrum of these UWB